1. Field of the Invention
The invention concerns impellers and, in particular, impellers for use in ring compressors.
2. Description of the Prior Art
When using a ring compressor employing an impeller to compress gases to pressure ratios of more than 1.2, the compressibility of the gas is found to have a detrimental effect on the compressor operation. In particular, the gas compressed into the blade cells (i.e., the regions between the impeller blades) is dragged across the break situated between the entrance and the exit openings of the side channel of the compressor. It then expands on the suction side of the compressor into the side channel, thereby causing a decrease in the useful draw in flow. Such a decrease in the draw in flow, in turn, limits the attainable pressure ratio and the attainable efficiency of the compressor.
It is therefore an object of the present invention to provide an impeller for a ring compressor which results in improved performance of the compressor.